When scientists talk about the cryosphere, they mean the places on Earth where water is in its solid form, frozen into ice or snow. Read more ...

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People sometimes wonder if the weather they are experiencing locally, such as the heavy snow that fell in February 2011 over the Northeastern U.S., is connected to decreasing Arctic sea ice. Scientists are exploring a possible connection. Credit: NASA Earth Observatory.

Over the 2010 to 2011 winter, news stories suggested a potential connection between a warming climate, low Arctic sea ice extent, and unusually cold weather this winter in the U.S. and Europe. What do scientists know about how sea ice affects the weather?

Scientists have been exploring a possible link, but the question is far from settled. It makes sense that changing sea ice conditions could affect weather in the Arctic and other parts of the world. During the colder months, sea ice insulates the relatively warm ocean from the colder atmosphere. As sea ice declines, more heat can escape to the atmosphere in the fall and winter, affecting wind patterns, temperature, and precipitation. Continue reading →

Last week, a reader of Arctic Sea Ice News & Analysis asked what we know about Arctic sea ice extent before the satellite records began in 1979. Those records show that Arctic sea ice has been declining at an increasing pace since 1979—enough data to see a strong signal of climate change. But scientists also want to know what sea ice was like before satellites were there to observe it. Mark Serreze, NSIDC director and research scientist, said, “The better we understand how the climate system behaved in the past, the better we can understand and place into context what is happening today.” What do we know about sea ice conditions before 1979, and how do we know that?

Sea ice charts of the Arctic Ocean show that ice extent has declined since at least the 1950s. Credit: NSIDC and the UK Hadley Center

Historical data on sea ice

Scientists have pieced together historical ice conditions to determine that Arctic sea ice could have been much lower in summer as recently as 5,500 years ago. Before then, scientists think it possible that Arctic sea ice cover melted completely during summers about 125,000 years ago, during a warm period between ice ages. Continue reading →